Test `Regress314573_VeryLongPaths` fails when long paths are not enabled on Windows

I set up a new machine and see a failure in `Regress314573_VeryLongPaths`:

```
Assert.Equal() Failure: Values differ
Expected: 1
Actual: 0
at Microsoft.Build.UnitTests.ResolveAssemblyReference_Tests.Miscellaneous.Regress314573_VeryLongPaths() in S:\msbuild\src\Tasks.UnitTests\AssemblyDependency\Miscellaneous.cs:line 4919
```

With this in the log

```
ERROR MSB3248: Parameter "AssemblyFiles" has invalid value "C:\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\A.dll". Path: C:\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\A.dll exceeds the OS max path limit. The fully qualified file name must be less than 260 characters.
```

I think the test was trying to detect that that didn't cause a failure when it was written long long ago.

I'm not sure the current behavior is wrong though . . .